superseded: [PATCH pve-network] sdn: push mapping changes from the ipam API to the dhcp backend

[Hannes Laimer <h.laimer@proxmox.com>]

superseded-by:
https://lore.proxmox.com/pve-devel/20260905092106.10567-1-h.laimer@proxmox.com/T/#u

On 2026-09-02 14:54, Hannes Laimer wrote:
> Mapping edits through the API only wrote the IPAM record and the
> cache, the dhcp backend was never told, so dnsmasq kept serving
> stale reservations until a later guest start in the zone happened
> to sweep them.
> 
> Push the MAC's current answer after each create, update and delete,
> removing the old reservation first, since a re-add alone leaves a
> stale address behind when only one of the MAC's two addresses was
> deleted. The push is best effort, the record write stays
> authoritative. Mapping removal was dispatched to the plugins but
> implemented nowhere and never called, add the dnsmasq
> implementation for it.
> 
> Signed-off-by: Hannes Laimer <h.laimer@proxmox.com>
> ---
>  src/PVE/API2/Network/SDN/Ips.pm     | 18 ++++++++++++++++
>  src/PVE/Network/SDN/Dhcp/Dnsmasq.pm | 32 ++++++++++++++++++++++++++++-
>  src/PVE/Network/SDN/Dhcp/Plugin.pm  |  5 +++++
>  3 files changed, 54 insertions(+), 1 deletion(-)
> 
> diff --git a/src/PVE/API2/Network/SDN/Ips.pm b/src/PVE/API2/Network/SDN/Ips.pm
> index 5ff05e7..fc76c90 100644
> --- a/src/PVE/API2/Network/SDN/Ips.pm
> +++ b/src/PVE/API2/Network/SDN/Ips.pm
> @@ -13,6 +13,17 @@ use PVE::RESTHandler;
>  
>  use base qw(PVE::RESTHandler);
>  
> +my sub update_dhcp_mapping {
> +    my ($vnet, $mac) = @_;
> +
> +    eval {
> +        my ($ip4, $ip6) = PVE::Network::SDN::Vnets::get_ips_from_mac($vnet, $mac);
> +        PVE::Network::SDN::Dhcp::remove_mapping($vnet, $mac);
> +        PVE::Network::SDN::Dhcp::add_mapping($vnet, $mac, $ip4, $ip6) if $ip4 || $ip6;
> +    };
> +    warn "could not update dhcp mapping for $mac: $@" if $@;
> +}
> +
>  __PACKAGE__->register_method({
>      name => 'ipdelete',
>      path => '',
> @@ -46,6 +57,8 @@ __PACKAGE__->register_method({
>          eval { PVE::Network::SDN::Vnets::del_ip($vnet, $ip, '', $mac); };
>          die "$@\n" if $@;
>  
> +        update_dhcp_mapping($vnet, $mac);
> +
>          return undef;
>      },
>  });
> @@ -82,6 +95,8 @@ __PACKAGE__->register_method({
>  
>          PVE::Network::SDN::Vnets::add_ip($vnet, $ip, '', $mac, undef);
>  
> +        update_dhcp_mapping($vnet, $mac);
> +
>          return undef;
>      },
>  });
> @@ -132,6 +147,9 @@ __PACKAGE__->register_method({
>          }
>  
>          die "$error\n" if $error;
> +
> +        update_dhcp_mapping($vnet, $mac);
> +
>          return undef;
>      },
>  });
> diff --git a/src/PVE/Network/SDN/Dhcp/Dnsmasq.pm b/src/PVE/Network/SDN/Dhcp/Dnsmasq.pm
> index 477b700..4677330 100644
> --- a/src/PVE/Network/SDN/Dhcp/Dnsmasq.pm
> +++ b/src/PVE/Network/SDN/Dhcp/Dnsmasq.pm
> @@ -6,7 +6,7 @@ use warnings;
>  use base qw(PVE::Network::SDN::Dhcp::Plugin);
>  
>  use Net::IP qw(:PROC);
> -use PVE::Tools qw(file_set_contents run_command lock_file);
> +use PVE::Tools qw(file_get_contents file_set_contents run_command lock_file);
>  
>  use File::Copy;
>  use Net::DBus;
> @@ -136,6 +136,36 @@ sub add_ip_mapping {
>      update_lease($dhcpid, $ip4, $mac);
>  }
>  
> +sub del_ip_mapping {
> +    my ($class, $dhcpid, $mac) = @_;
> +
> +    my $ethers_file = ethers_file($dhcpid);
> +
> +    my $reload = undef;
> +
> +    my $removeFn = sub {
> +        my @lines = split(/\n/, file_get_contents($ethers_file));
> +        my @remaining = grep {
> +            my ($parsed_mac) = split(/,/, $_);
> +            !defined($parsed_mac) || $parsed_mac ne $mac;
> +        } @lines;
> +
> +        return if scalar(@remaining) == scalar(@lines);
> +
> +        file_set_contents($ethers_file, join("\n", @remaining) . "\n", 0644);
> +        $reload = 1;
> +    };
> +
> +    PVE::Tools::lock_file($ethers_file, 10, $removeFn);
> +
> +    if ($@) {
> +        warn "Unable to remove $mac from the dnsmasq configuration: $@\n";
> +        return;
> +    }
> +
> +    systemctl_service('reload', "dnsmasq\@$dhcpid") if $reload;
> +}
> +
>  sub configure_subnet {
>      my ($class, $config, $dhcpid, $vnetid, $subnet_config) = @_;
>  
> diff --git a/src/PVE/Network/SDN/Dhcp/Plugin.pm b/src/PVE/Network/SDN/Dhcp/Plugin.pm
> index b5d32fa..6cbb8a2 100644
> --- a/src/PVE/Network/SDN/Dhcp/Plugin.pm
> +++ b/src/PVE/Network/SDN/Dhcp/Plugin.pm
> @@ -27,6 +27,11 @@ sub add_ip_mapping {
>      die 'implement in sub class';
>  }
>  
> +sub del_ip_mapping {
> +    my ($class, $dhcpid, $mac) = @_;
> +    die 'implement in sub class';
> +}
> +
>  sub configure_range {
>      my ($class, $config, $dhcpid, $vnetid, $subnet_config, $range_config) = @_;
>      die 'implement in sub class';